Combine two versions of print_statistics() in java.cpp

https://github.com/openjdk/jdk/blob/f61499c73fe03e2e3680d7f58a84183364c5c5ac/src/hotspot/share/runtime/java.cpp#L230-L386

The non-product version of print_statistics() can be compiled in product builds with very little modification. So it makes no sense to have two versions.